The substantial increase in the use of pagers, car phones, cordless telephones, and other wireless personal communication devices testifies to the fact that mobile communications is perceived by many to be an essential element of life in the 1990's. However, even with these devices, many people are still effectively out of reach because callers do not know which of their many numbers to call.
Communications service providers have proposed a personal number calling or PNC solution to this problem: a personal phone with a single number. The interworking between the plethora of wireline and wireless networks that is required to allow all people to be reached regardless of their location will take a number of years to accomplish.
In the short-term (i.e., the next one to five years), a number of interim solutions to this personal mobility problem are anticipated that will use adjunct processors and the existing wireline and wireless communications infrastructure to achieve the desired end-user functionality. In the longer term, some of these features will be incorporated into the public switched network through the Advanced Intelligent Network (AIN), and into PBXs and other switches through software additions.
The issue of obtaining a physical connection between caller and called party is not the only problem that must be addressed. Informal research on user attitudes about personal communications has revealed that the idea of being accessible 24 hours a day, 7 days a week to anyone that knows your personal number is an anathema to even the most enthusiastic embracers of new technology. The problem: answering the phone can be a waste of time and even annoying when you are interrupted from something more important. This is one of the objectives of Personal Communications Networks, e.g. "The difference with PCN will be the ability to maintain control without losing calls, screening them in real time so that important calls get through while others are deferred, but none are actually lost." Thus, the problem is how does one allow people to be reachable anywhere and any time, but only by those individuals that they want to reach them?
Studies of highly mobile individuals (e.g., sales people, doctors) show that a good secretary or receptionist is the currently favored solution. However, good receptionists are hard to find, relatively expensive to employ and not on duty 24 hours a day.